rgb cable problem

[stuntpup]

I thought i would try connecting my amiga 1200 to the samsung lcd telly so bought an rgb cable..

picture is all terrible and wavy and i can see like a green bar rolling up and the words NO GROUND i think (it moves fast but i think thats what it says) ..
i have tried two rgb cables now .. so i know its not a faulty one.

anyone know what this issue is ? and how i can fix it ?

cheers

[Zetr0]

@stuntpup

'elo

looks like a right pickle... okay, before we take what the monitor is saying as truth, then it might be an idea to test it on another monitor (say tv). If you are still receiving crap signal, then perhaps your A1200 RGB port is not providing ground as it says.

However if it works then its highly possible that the LCD wont sync to 15Khz RGB IN... have you attempted a composite scart connection?

[stuntpup]

hello all mighty zetr0

yeah composite is fine .. its what i was using before, but wasnt happy with picture quality.

i will double check with another tv tomorrow.

i had a playstation2 connected to the rgb socket on the samsung and that was fine.. but maybe it wasnt rgb .. i dunno ..

thanks..

[Zetr0]

@stuntpup

if in doubt take pictures (then post them)

[alexh]

A LOT of Amiga RGB SCART cables are wired wrong. They have the wrong voltages / signals on pins 8 and pins 16.

Pin 8 = 9.5v - 12v
Pin 16 = 1v - 3v

If the SCART on your LCDTV follows the rules to the letter and the voltages are wrong on your cables then you will either get a black screen or who knows what. Especially if it accepts S-Video and is set to S-Video in the menu system.

You need to double check the wiring in your cables, check any settings in the LCD menu system.

[stuntpup]

hi .. well i tried the amiga on another telly..

Goodmans crt widescreen with two scarts at the back. (one rgb one composite)

rgb scart works !
the composite scart just shows a blank picture .. i can just about make the icons out so it is trying to show something ..

so composite scart on the goodmans doesnt work.


the samsung lcd again with two scarts (one rgb, one composite)
from composite scart just a white picture..
from rgb i get a picture but with the wavy lines and moving green bar that says no ground.

i would prefer to use it on the lcd telly.. do i have any other options to do this ? .. is it worth trying it through a scart block ?

cheers

[alexh]

Originally Posted by stuntpup

i tried the amiga on another telly..

Goodmans crt widescreen with two scarts at the back. (one rgb one composite)

rgb scart works !
the composite scart just shows a blank picture ..

There is no composite video on a regular Amiga RGB SCART cable. If connected to a composite RGB socket, a blank screen is exactly what to expect.

is it worth trying it through a scart block ?

No. You'll undoubtably have to rewire the SCART cable to put the right voltages on pins 8 & 16!

[stuntpup]

rewire ?

is that as easy as it sounds ? !!

[alexh]

It depends on your skills. From your posts, I would say probably not.

Do you have access to a multi-meter, a soldering iron and a selection of resistors?

First you need to check the wiring, open the SCART end of the cable and check what is connected to pins 16 & 8.

Trace them back to the Amiga end of the cable and see which pins they are wired to.

Once you have that information I can advise.

If the Playstation RGB cable works in RGB... then the Amiga will work (eventually).

[stuntpup]

yeah thats pretty much beyond me im afraid ..

thanks for your input tho

[Zetr0]

@stuntput

if you want, i can lump together a schematic for you.... its quite simple, just like an overly large plug

[stuntpup]

@zetr0 .. ok i will give it a go .. if there is any soldering i could be in trouble .. haha

what miffs me is the fact i bought two cables advertised as amiga rgb/scart .. when in reality it should have been rgb/scart that only works on some televisions.
in fact when i get a moment i will be putting my review of said cable on amigakit !

bah humbug haha

[Zetr0]

if you could take pictures m8, you must understand that both Alexh and I are *assuming* that your lead has the pins incorectly figged... and as you know... to assume makes an ASS out of U an ME..

insofar as soldering if there is any i would be supprised if there is more than two welds to do...

[alexh]

Not necessarily incorrectly wired, it could just be incorrect / no resistor values.

1-3v on Pin16 is impossible without resistors considering Amiga 23-pin D only has 5v.

On older TV's 5v may work but if you are an LCDTV 100% following the spec, I dunno what would happen.

If you bought your cable from AmigaKit... I would be inclined to think that they would have tried their best.

Try an INTERLACED amiga screen, (workbench) see if that works.

[stuntpup]

I have attached some pictures of each end of the cable i have

hopefully you can make everything out ok !

[Zetr0]

@stuntpup

From the diagnosis, I have discovered that the Scart end is missing (pin 5) Blue Ground...

You can source this from either the Shield[21] / Pink[9] or RED[13]

It would seem that your Samsung is fussy about the All RED/GREEN/BLUE must be grounded.... interesting... i supose that IS spec... most wont have that problem as most grounds are tied to shield or all gounds are tied and then sourced from that (execept digital grounds btw).... strange... but kinda cool... in a strange way

It might be wise to let AK know that some monitors are no longer tie-ing ALL thier grounds

anyways two welds with a soldering iron and you should be up and running check out pic that should put you in the picture

[stuntpup]

ok .. lets see if i have this straight !

im desoldering one of the wires .. pink looks the closest so lets say that un.
then splitting it so one goes to pin 5 and one back to pin 9

[Zetr0]

yepo thats it

[stuntpup]

cheers for that .. will keep you posted !

[killergorilla]

I think a lot of Amiga RGB cables are like this, mine had problems last time I tried to use it with a modern TV. (as did one I butchered trying to fix!)

It was fine with the old 1084.

I might take a look at the pins/wires and see if it's the same case with mine.